PHILADELPHIA â€” Itâ€™s not every day that researchers get access to a mouse thatâ€™s been to space and back, and, with the Space Shuttle program now scuttled, future chances will be even harder to come by.
Associate professor Elisabeth Barton and postdoctoral fellow Anastasios Philippou of the Anatomy and Cell Biology Department of the University of Pennsylvania School of Dental Medicine jumped at the chance to work with the mice that were part of the shuttleâ€™s final mission.
â€śWe had just completed a grant from NASA, studying how muscles sense load and the molecular pathways involved, but all of our experiments involved stretching tissues and cells in the lab,â€ť Barton said.
â€śBecause of our previous work with NASA, we were able to write a proposal to study samples taken from mice that went up on the shuttle for a different experiment,â€ť she said. â€śWhen youâ€™re in space, thereâ€™s no load on your muscles and we want to understand the consequences.â€ť
Barton and Philippou study the sarcoglycan complex, a combination of proteins in muscle cells. On earth, leg muscles bear the weight of an organism whenever itâ€™s standing, but without gravity there is nothing to support. The mouth muscles involved in chewing, however, are less dependent on gravity to function.
â€śOur first experiments will be on the histology, or the appearance of the cells of these muscles,â€ť Philippou said. â€śThen weâ€™ll look at them at the molecular level.â€ť
â€śWeâ€™re looking for clear differences in loading between jaw muscles and limb muscles in mice,â€ť Barton said. â€śWe can use the database we developed in our previous NASA work to see how important this complex is to load sensing.â€ť
The sarcoglycan complex is also involved in diseases such as muscular dystrophy. Understanding how these proteins are involved with the weakened muscles of those with the disease could help astronauts prevent similar atrophy that stems from long periods of living in microgravity.
â€śIf we could use this complex to trick the muscles into thinking theyâ€™re loaded, that would be a great advantage for astronauts,â€ť Barton said. â€śComparing limb and jaw muscles will also allow us to see whether there are effects of microgravity on muscles beyond the lack of load.â€ť